Drying process and apparatus using a coherent light source



S. A. SPUNT Dec. 20, 1966 DRYING PROCESS AND APPARATUS USING A COHERENTLIGHT SOURCE Filed April 1, 1964 FILAMENT GATHERER E S m m w m E H SDIAMETER MEASURER AT OR NEY United States Patent 3,292,270 DRYINGPROCESS AND APPARATUS USING A COHERENT LIGHT SOURCE Shepard A. Spunt,147 Coolidge St., Brookline, Mass. Filed Apr. 1, 1964, Ser. No. 356,60716 Claims. (Cl. 34-1) This invention relates to the manufacture oftextile fibers or yarns. More specifically, this invention concerns amethod of drying these materials through the use of coherent light wavessuch as produced by a laser.

In the past, yarn or textile fibers, that is, the wide range ofsynthetic fibers such as rayon, dacron and orlon; and inorganics such asglass, have generally been prepared by heating the components untilmolten, and then forcing the molten mass through orifices to formfilaments. Cotton and wool have been formed into threads by drawing themfrom a disordered mass. Nylon has been made from a cold forming process.Any of these yarns or fibers can then be bound, twisted, or plyed intostrands if desired. From the forming stage, the material is sized, ifnecessary, and wound upon a winding spindle. The strands are often wetfrom the sizing operation and/or forming.

Now the art has generally desired to dry the strands completely or to aspecific degree of moisture content before they are placed upon thespindle; however, such attainments have not been realized. Inherently,the filaments come from the orifices in varying diameters between about0.0005 to 0.12 inch and at great velocities, frequently as high as about5,000 to 15,000 feet per minute and sometimes higher. With conventionalmethods of drying using radiant heat, the temperature must be preset forthe average diameter and velocity of the material passing through thedrying stage. If the diameter decreases even for an instant, thematerial can be scorched, weakened and sometimes broken, while if thetemperature is too low, the material is dried only partially. Sincebreakage is least desirable, the art has compromised upon partial dryingbefore winding and then baking the entire package in an oven. It hasbeen difiicult to dry the filaments as they are formed because it hasbeen impossible to change the temperature of the radiant heating devicequickly in relationship to the diameter and mass of the strand passingthrough its Waves because of the time lag in changing the temperature.The art then has compromised upon hollow, perforated winding spindle sothat when placed in an oven, heat may pass into the winding in a fairlyuniform manner. Even with such devices, however, the drying is onlypoor, at best, because the heat does not uniformly penetrate. Quiteapparently, this solution to the problem is unsatisfactory because ofthe prolonged delay during baking and inadequate drying period, andcostly material handling.

Furthermore, while the strand is being wound upon a winding spindle, thevelocity gradually changes due to the gradually increasing diameter asthe spindle fills. Hence the drying temperature must be modified toreflect the velocity of the strand passing therethrough. Ordinaryradiant heat furnaces were incapable of modifying their temperatures inaccordance with the changing velocities.

Quite unexpectedly, I have discovered that drying can be performed uponsuch materials even though the diameter and mass may vary and eventhough they pass through the drying stage with great velocities. I havediscovered that a source of coherent light waves such as produced bydevices commonly known as lasers or masers will perform such operations.Then coherent light sources can be instantaneously modified to changethe heat produced by the light waves; and hence, drying of the strandsof varying diameters and masses can be instantaneously regulated.

3,292,270- Patented Dec. 20, 1966 "ice According to my invention, Imonitor the diameter and if desired, the velocity, of the strandspassing from the formmg stage and relay this information to a source ofcoherent light which will be programmed to modify instantaneously theenergy produced in response to the input. Generally, a so-called gaslaser is preferred because of its flexibility and freedom frommaintenance; however, the ruby type also has applicability.

Accordingly, the primary object of my invention is drying fibers oryarns as they pass from a forming stage and before they are wrapped upona drying spindle.

Another object of my invention is the complete drying, when desired, ofsuch materials, and thus the elimination of baking the wrapped strandsin an oven as a separate process step.

A feature of my invention is using a source of coherent light to dry theyarns or fibers.

Another feature of my invention is monitoring the diameter of strands ofmaterial and relaying this information to a source .of monochromaticlight and thereby change its intensity.

And yet another feature of my invention is monitoring the velocity ofthe strand passing through the source of coherent light to dry itWithout scorching.

An advantage of my invention is that materials of varying diameters canbe dried as formed at exceedingly throughput velocities withoutscorching or breaking them.

The many other objects, features and advantages of my invention willbecome manifest to those conversant with the art upon reading thefollowing specification in which preferred embodiments of my inventionof drying yarns and fibers are shown in the accompanying drawings anddescribed herein by way of illustrative examples.

Of these drawings, the figure is a diagrammatic, schematic view of anapparatus which can be used with my process of forming, drying andwrapping yarns or fibers upon a spindle.

My invention will be particularly described with reference to themanufacture of glass fibers although as has been indicated, othermaterials such as rayon, dacron, and orlon which are made by a hotforming process can also be dried. Additionally, cold forming strandoperations can utilize my invention along with natural fiber processessuch as cotton and wool manufacture. With particular reference to theglass fiber, a diagrammatical y illustrated apparatus for forming andwinding the material upon a spindle is shown. The apparatus comprises achamber 5 containing a number of glass marbles (not shown). From conduit10, the marbles are directed into a furnace 14 where they are heated toform a molten liquid. The liquid flows by gravity or is extruded andsubsequently attenuated into fine glass filaments 17 through a bushing15 having a plurality of orifices.

When .forming continuous strands from finely drawn filaments bycollecting the filaments at a guide, the common practice is to providethe guide with an applicator for evenly coating the surface of thefilaments with material such as a lubricant, sizer or binder. Thefilaments are converged and grouped together to form a strand as theypass over the guide and usually are simultaneously coated with theliquid to prevent the filaments within the strand from abrading eachother. Also, the liquid can give mass integrity to the group of strandedfilaments thereby preventing loss from either fraying or breaking away.

Disposed beneath the gathering device 20 is a diameter indicating device22 which measures the diameter (and the mass) of the strand 18 passingtherethrough. When the diameter of the strand 18 is measured, theinformation which is relayed to a metering system 24 which in turnrelays the information to the laser 25, the source of coherent light.Because of the instantaneous response to changes in diameter, and thusinherently mass, to which the source 25 responds, the strand 18 can bedried to the exact degree which is desired. The light from the laser 25radiates from either end and is focused by mirrors 27 upon the strand18. Since the light emitted from the laser can be instantaneouslyregulated, the heat produced can be varied to compensate for even minuteand rapidly changing variations in the diameter of the strand 18.

If desired, the diameter indicating device 22 can be modified to measurethe velocity of the strand 18 passing therethrough.

I prefer to use the well-knovm, helium-neon gas laser which providescontinuous operation at several infrared wave lengths of 11, 180,11,530, 11,600, and l2,070.A.; the strongest of these being the 11,530A. radiation line. Alternatively, a system which utilizes a triggeringmethod to increase the pulse rates of ruby lasers can be used. Insteadof switching the laser pulse source fully on to make the ruby laser,which is the conventional method, just enough pulse excitation isapplied to start the laser action. Immediately after the laser actionbegins, the excitation source goes off and the laser excitation stops.At this time, there are a large number of ions at a high energy state,since therelaxation time between the upper state (E level) and theground state is in the order of several microseconds. A relatively weakexcitation pulse can then restart the laser action. About 100microseconds later, another excitation source supplies a short durationlight pulse of low energy to the ruby causing it to lase light pulsesthat follow at 100 microsecond intervals provide 100,000 pulses persecond. Generally, the structure utilized for such operation includestwo spiral, coaxial flash tubes encircling the ruby. One of the flashtubes is smaller and is disposed nearer tothe ruby and provides thetrigger excitation pulses and the larger tube which surrounds the innerflash as well as the ruby provides the 200 microseconds preparationpulse.

It is apparent that changes and modifications may be made within thespirit and scope of the instant invention; however, it is my intentionto be limited only by the appended claims.

As my invention I claim:

1. A process for drying strands, the steps which comprise: passing saidstrand through energy waves generated by a coherent light source;varying the intensity of said energy Waves in response to the diameterof the passing strand, thereby drying it and then winding the driedstrand upon a spindle.

2. The process according to claim 1 wherein the strand is a glass fiber.

3. The process according to claim 1, wherein the strand is an organicfiber.

4. A process for drying strands, the steps which comprise: passing saidstrand through energy wavesgenerated by a coherent light source; varyingthe intensity of said energy waves in response to the velocity of thepassing strand, thereby drying it and then winding the dried strand upona spindle.

5. The process according to claim 4 wherein the intensity of thecoherent light source is also varied in re.

sponse to the diameter of the, passing strand.

6. A process for drying strands, the steps which com,- prise: measuringthe diameter of said strand, passing said strand through energy waves,generated by a coherent light means, changing the intensity of saidlight means in relation to the measured diameter of the strand passingtherethrough, thereby drying it and then Winding the dried strand upon aspindle.

7. The process according to claim 6 wherein the velocity of the strandis measured and the intensity of the energy waves is modified inrelation thereto.

8. The process according to claim 6 wherein the strands pass throughsaid energy waves at a velocity greater than 1 about 5000 feet perminute. 9. A process for drying strands, the steps which comprise:generating energy Waves from a coherent source of light; passing saidstrand through said energy waves thereby drying it and Winding the driedstrand upon a spindle.

10. A process for drying strands, the steps which come prise: generatingenergy waves from a coherent source,

of light;n1easuring the diameter of said strand; passing said strandthrough said energy waves and modifying the intensity of said lightsource in relation to the. measured diameter of the strand passingtherethrough.

11. The process according to claim 10 wherein the.

strand is glass fiber.

strand is an organic fiber.

13. Apparatus comprising, means for forming a strand of fiber; means formeasuring the diameter of said strand of fiber; coherent light sourcemeans disposed to focus its energy waves upon said strand; means forchanging the intensity of the light radiated from said coherent light'source means in relation to the measured diameter. re-.

layed from said diameter measuring means; means for winding said strandupon 'a spindle.

14. The apparatus according to claim 13 wherein the coherent lightsource means is a gas laser.

15. The apparatus according to claim 13 wherein the- References Cited bythe Examiner UNITED STATES PATENTS 3,066,999 12/1962 Nakajo et al.264-205 FOREIGN PATENTS 125,669 l/1960 Russia.

FREDERICK L. MATTESON JR., Primary Examiner. N J. C M E amin 12. Theprocess according to claim 10 wherein the,

9. A PROCESS FOR DRYING STRANDS, THE STEPS WHICH COMPRISE: GENERATINGENERGY WAVES FROM A COHERENT SOURCE OF LIGHT; PASSING SAID STRANDTHROUGH SAID ENERGY WAVES THEREBY DRYING IT AND WINDING THE DRIED STRANDUPON A SPINDLE.